Wireless receiving system



Oct. 15, 1929. ESAU WIRELESS RECEIVING SYSTEM Filed June 1924 INVENTOR ABRAHAM ESAU BY TTORNEY Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE ABRAHAM nsAU, or BERLIN, GERMANY, ASSIGNOR To GnsnLLscirArr run nnnnr- LOSE TELEGRAPHIE M. 13. 11., or BER-LIN, GERMANY, A oonronnrron 0F enn- MANY WIRELESS :ancnivrne sYsrnM Application filed June 5, 1924, Serial No.

My invention relates to wireless receiving systems in which means is provided for preventing the reception of various disturbances but yet allowing the reception of the signals.

An object of the invention is to provide such a system which will eliminate disturbances coming from sending stations other than the one whose signals it is desired to receive, which will eliminate atmospherics which are periodical, or sustained, or directional, and finally which will eliminate atmospherics of very short duration.

Other objects will be appareiit from the following description and claims when considered with the accompanying drawing in which:

The single figure represents an arrange ment embodying my invention.

In order to eliminate atmospherics and disturbances caused by other wireless stations, two methods have been used up till now. One method was by the employmentin the receiving station of an aerial arrangement which had a particular directive efiect, so that the signals coming from the transmit ting direction could be easily distinguished from signals coming from any other direction because of their much greater intensity. The other method for eliminating disturbances was by equipping the receiving station with compensating means which had to elimi nate the disturbing oscillations in the re ceiver.

Both methods are well adapted for eliminating disturbances caused by other transmitting stations, but they are insufficient for eliminating atmospherics. The intensity of the pulses of current caused by disturbances can, or" course, be considerably diminished in comparison with the intensity of the signal waves, it these disturbances do not come from the transmitting direction and if a directional aerial is used. As practice has shown that atmospherics really very often come from a certain direction, a certain freedom from 717,916, and in Germany June 13, 1923.

troubles can be attained by using a directional receiving arrangement. 'lhe application of this directional eiiect, however, fails if these disturbances come from those directions for which the receiving intensity of the aerial arrangement is large, and ifurthermore if the intensity of the disturbances is very large.

According to the second method as, for instance, according to the discoupling method (that is where the energy in one branch of the receiving system is made to compensate the energy in another branch) such disturbances which occur in the shape of impressed oscillations can be completely eliminated, but atmospherics can be decreased only to a cer tain extent, because the resonant circuits used -for the compensating connection are excited by the atmospherics and then oscillate in their natural frequencies.

In order to eliminate these oscillations excited by a shock, the so-called two-way connection is successfully employed. According to this method the oscillations of the aerial are led through two oscillatory circuits which are detuned to one another but have the same timeconstant. Then the oscillations are rectified and led to the common receiving system in opposite sense. This method is however only effective the atmospheric consists only of a very short shock. But the atmospherics which disturb the receiving circuit are shocks which differ very much from one another. If the shock has a longer duration or, if it is distinctly periodical, the natural oscillations of the two circuits of the two-way connection are combined with an impressed oscillation, which, of course, cannot be compensated at the same time and consequently considerably disturbs the receiving of the signals. It may be seen from the preceding that only partly satisfactory results could be attained by these two different methods for eliminating disturbances. Up till now according to the de-.

sired purpose, either the one method or the other was used.

According to the present invention, a freedom from troubles completely sufficient for practice, is attained by the simultaneous application of both methods. That is, a receiving aerial system with a directional effect is used together with a compensating arrangement. Disturbances coming from certain directions are completely eliminated by the directional efii'ect of the aerial system; those disturbances which do not come from that direction which corresponds to the maximum receiving intensity, are considerably decreased. 7 Those disturbances which are not completely eliminated by the directional effect of the aerial, are annulled by the compensating arrangement. This compensating arrangement can be applied in such a way that the radio frequency oscillations of the disturbances are compensated, as, for instance, according to the discoupling method for eliminating disturbances caused by other stations. It is also. possible to compensate the disturbing oscillations after they are transformed into audio frequency oscillations or after beingrectified, as, for instance, according to the above-mentioned two-way connec tion using two circuits of equal time-constant. Finally it is also possible to compensate the radio frequency oscillations and the audio frequency oscillations at the same time.

The drawing shows an example of the present invention. R R A constitute an aerial system for directional receiving. The frame aerials R and R are combined by. connecting Y the mid pointsof coils 1 and 2 to earth across coil A, sothat the two frame aerials together with the earth connection represent a highaerial. The frame aerial energy from loops R R is led by means of couplings 3 and 4 respectively across two circuits K and K and thence by means of couplings 5 and 6 to the common receiving circuit E which may also be aperiodic. The open aerial energy picked up. by frames R and R is led by means of coupling? across an oscillatory circuit B and thence by means of coupling 8 to circuit E and the right phase of the voltage generated in the receiving circuit E by said open aerial energy is adjusted by the corresponding detuning of the oscillatory circuit B. This already known arrangement for directional receiving is combined with a compensating arrangement by leading the oscillations from the common receiving circuit E to the rectifying arrangements G and G across two oscillatory circuitsT, and T, which are detuned to one another but have the same time-constant. Circuits T and T are coupled to circuit E by means of couplings 9 and 10 respectively and are coupled to rectifier arrangements Gr and 'Gr by means of couplings 11- and 12 respectively.

two thermionic tubes 13 and 14 with their filaments connected together and to the midpoint of coil 15. The ends of coil 15 are connected respectively to the grids of tubes 13 and 14. Plate voltage is supplied the tubes 13 and 14 by means of B-battery 16 acting thru coil 17. Tubes 13 and 14. work on asymmetrical parts of their characteristics so as to give the desired rectification.

Rectifier arrangement G is made up of identical apparatus with the arrangement G similar apparatus being designated by the same reference characters primed.

Coils 17 and 17 oppose each other in their effect on armature S of the indicating device. It will easily be seen that when oscillatory circuits T and T are set into vibration at their natural periods by a shock of static, the damped oscillations having equal time constants, after being rectified will neutralize each other in their effect on the armature S.

In case it does not concern the elimination of oscillations excited by a shock but of undamped oscillations of a disturbing transmitter, the two transferring circuits T and T can be used as secondary circuit and auxiliary circuit of a discoupling arrangement, and act in this case upon the rectifying circuit.

Having described my invention, what I claim is:

1. In a Wireless system adapted for the elimination of electrical disturbances, an aerial system with means comprising two branches and a common portion adapted for directional receiving, a common receiving circuit, coupling means for said aerial system and said common receiving circuit comprising individual circuits for each of said two branches and said common portion, the coupling circuit of said common portion being an adjustable oscillatory circuit, a compensating arrangement comprising two separate and oppositely acting rectifying circuits and means comprising two detuned oscillatory circuits for leading oscillations from said common receiving circuit to the rectifying circuits whereby electrical disturbances may be neutralized.

2. In an aerial sytsem adapted for the elimination of electrical disturbances, a grounded inductance, a plurality of directional antennae variably connected to said inductance, a common receiving circuit coupled to each of. said directional antennae, means comprising an adjustable oscillatory circuit for coupling said inductance to said receiving circuit, means for neutralizing electrical (listurbances fed to said receiving circuit comprising two separate and oppositely acting rectifying means and means for leading oscillations from said common receiving circuit to said rectifying means.

3. In a wireless receiving system adapted for the elimination of electrical disturbances, a grounded inductance, a plurality of ABRAHAM ESAU. 

